From 0610ccb66131e8494f990af85d152c73d7534d90 Mon Sep 17 00:00:00 2001
From: avg <avg@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Thu, 17 Nov 2016 15:19:33 +0000
Subject: [PATCH] MFC r308247: MFV r308222: 6051 lzc_receive: allow the caller
 to read the begin record

git-svn-id: svn://svn.freebsd.org/base/stable/10@308764 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 .../lib/libzfs_core/common/libzfs_core.c      | 42 +++++++++++++++----
 .../lib/libzfs_core/common/libzfs_core.h      |  7 +++-
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c b/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c
index c1ada8d6a..ee3158b4f 100644
--- a/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c
+++ b/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c
@@ -596,8 +596,9 @@ recv_read(int fd, void *buf, int ilen)
 }
 
 static int
-lzc_receive_impl(const char *snapname, nvlist_t *props, const char *origin,
-    boolean_t force, boolean_t resumable, int fd)
+recv_impl(const char *snapname, nvlist_t *props, const char *origin,
+    boolean_t force, boolean_t resumable, int fd,
+    const dmu_replay_record_t *begin_record)
 {
 	/*
 	 * The receive ioctl is still legacy, so we need to construct our own
@@ -642,9 +643,14 @@ lzc_receive_impl(const char *snapname, nvlist_t *props, const char *origin,
 		(void) strlcpy(zc.zc_string, origin, sizeof (zc.zc_string));
 
 	/* zc_begin_record is non-byteswapped BEGIN record */
-	error = recv_read(fd, &zc.zc_begin_record, sizeof (zc.zc_begin_record));
-	if (error != 0)
-		goto out;
+	if (begin_record == NULL) {
+		error = recv_read(fd, &zc.zc_begin_record,
+		    sizeof (zc.zc_begin_record));
+		if (error != 0)
+			goto out;
+	} else {
+		zc.zc_begin_record = *begin_record;
+	}
 
 	/* zc_cookie is fd to read from */
 	zc.zc_cookie = fd;
@@ -685,7 +691,7 @@ int
 lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
     boolean_t force, int fd)
 {
-	return (lzc_receive_impl(snapname, props, origin, force, B_FALSE, fd));
+	return (recv_impl(snapname, props, origin, force, B_FALSE, fd, NULL));
 }
 
 /*
@@ -698,7 +704,29 @@ int
 lzc_receive_resumable(const char *snapname, nvlist_t *props, const char *origin,
     boolean_t force, int fd)
 {
-	return (lzc_receive_impl(snapname, props, origin, force, B_TRUE, fd));
+	return (recv_impl(snapname, props, origin, force, B_TRUE, fd, NULL));
+}
+
+/*
+ * Like lzc_receive, but allows the caller to read the begin record and then to
+ * pass it in.  That could be useful if the caller wants to derive, for example,
+ * the snapname or the origin parameters based on the information contained in
+ * the begin record.
+ * The begin record must be in its original form as read from the stream,
+ * in other words, it should not be byteswapped.
+ *
+ * The 'resumable' parameter allows to obtain the same behavior as with
+ * lzc_receive_resumable.
+ */
+int
+lzc_receive_with_header(const char *snapname, nvlist_t *props,
+    const char *origin, boolean_t force, boolean_t resumable, int fd,
+    const dmu_replay_record_t *begin_record)
+{
+	if (begin_record == NULL)
+		return (EINVAL);
+	return (recv_impl(snapname, props, origin, force, resumable, fd,
+	    begin_record));
 }
 
 /*
diff --git a/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.h b/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.h
index d922ab55f..8ff00cc2d 100644
--- a/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.h
+++ b/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.h
@@ -68,10 +68,15 @@ enum lzc_send_flags {
 int lzc_send(const char *, const char *, int, enum lzc_send_flags);
 int lzc_send_resume(const char *, const char *, int,
     enum lzc_send_flags, uint64_t, uint64_t);
+int lzc_send_space(const char *, const char *, uint64_t *);
+
+struct dmu_replay_record;
+
 int lzc_receive(const char *, nvlist_t *, const char *, boolean_t, int);
 int lzc_receive_resumable(const char *, nvlist_t *, const char *,
     boolean_t, int);
-int lzc_send_space(const char *, const char *, uint64_t *);
+int lzc_receive_with_header(const char *, nvlist_t *, const char *, boolean_t,
+    boolean_t, int, const struct dmu_replay_record *);
 
 boolean_t lzc_exists(const char *);
 
-- 
2.45.0